The present invention relates generally to small firearm munitions (xe2x80x9cbulletsxe2x80x9d), and more particularly, to a casing (xe2x80x9cjacketxe2x80x9d) that surrounds a bullet, and a method for making the same.
Bullets with a copper jacket and lead core (xe2x80x9cstandard bulletsxe2x80x9d) are a nearly universal standard in both civilian and military applications. For example, it has been estimated that one manufacturer of small arms ammunition may distribute as many as 5 million standard bullets annually for civilian use. Additionally, the United States military has used standard bullets for decades.
Unfortunately, the use of standard bullets give rise to significant environmental problems. Standard bullets are, in fact, responsible for two major types of environmental hazards. Because 90-95% of the total weight of standard bullets is lead, these bullets have the potential to introduce large quantities of lead toxin into our environment. First, lead vapors and lead dust caused by the use of standard lead bullets in indoor shooting ranges are a significant hazard to employees and users of such ranges. Lead dust and vapors are released from bullets striking target back-stops. The small particles of lead released with each impact eventually permeate the air of these confined areas and may eventually cause serious health difficulties, while the presence of a jacket over a lead core bullet helps to reduce the hazards related to lead dust, any new bullet designs should consider this environmental hazard in the design.
In situations where a large number of standard bullets are fired outdoors, the lead presents a second environmental hazard. Bullets are often left in large quantities on the grounds of practice ranges and on battle fields. Despite the copper jacket surrounding the lead core of standard bullets, these bullets corrode. The lead from standard bullets leaches into the soil, eventually contaminating the soil, rain water run-off and ground water. The cost of hazardous waste clean-up of the lead is often significantxe2x80x94the cost of such a clean-up is, therefore, prohibitive for operators of outdoor shooting ranges. Consequently, the owners of such ranges do not voluntarily engage in a clean-up operation. Thus, lead contamination of the environment by standard bullets left on such ranges merely continues to grow.
In view of the environmental hazards resulting from firing and discarding standard bullets, it is desirable to develop a bullet which eliminates or reduces these hazards. One solution to the environmental hazards is to design bullets that do not contain a lead core. However, the non-lead core bullets present other problems. Such bullets often have a smaller mass than standard bullets. This difference in mass may result in a bullet of less stopping power. In other words, a bullet designed without a lead core may fail in its essential purpose. Furthermore, the small mass of non-lead bullets often leads to significant ricochet problems. A bullet having a weight of approximately 50% of a standard bullet may strike a target and ricochet as far back as to the shooter. Such ricochets present a great danger to target shooters, especially those who shoot in an indoor range. New bullet designs have been developed to address these problems. However, manufacturing new bullet designs requires significant expenditures for the design and construction of new manufacturing tools to accommodate the new bullet designs. Therefore, it is desired to create a bullet that has dimensions and capabilities very similar to those of standard bullets.
The manufacture and use of tungsten bullets is illustrative of additional problems presented by removing lead from bullet designs. Tungsten bullets do not create dusts or vapors when fired, and are inert when stored on the ground. However, tungsten is a very expensive material. The manufacture of tungsten bullets may cost as much as 16 times more than the cost of manufacture of standard bullets having a traditional lead core and copper jacket. Additionally, there is little information regarding the effect of tungsten in a wound. It is known, however, that tungsten powder produces tissue necrosis and that conventional x-ray equipment cannot locate tungsten within a human body. Therefore, a wound created by a tungsten bullet is difficult to treat. Thus, it is desired to produce a bullet, which does not present such problems related to diagnosis and treatment.
U.S. Pat. No. 6,095,052, issued Aug. 1, 2000 also results an alternative to lead core bullets. However, the bullet of this patent also fails to be a complete solution. The invention of this patent involves the attachment of zinc foil to a lead sheet. This sheet and foil are rolled and pressure formed into a bullet having generally helical layers of lead sheet and zinc foil. This method provides a zinc layer over the lead core of a bullet and may be effective in preventing a lead contained in a standard bullet from leaching into soil or ground water. However, the process for making such a bullet is difficult and expensive. Given the high volume of bullets produced by even a single manufacturer, adding complexity to the manufacturing process is likely to have a significant impact on the cost of producing bullets and, by necessary implication, on the cost of purchasing bullets. Therefore, it is desired to provide a bullet which is environmentally friendly but which is reasonable in cost of materials and manufacture.
The advantages of the present invention are achieved by providing an enviromnentally safe bullet that maintains the performance characteristics of standard bullets. The bullet jacket of the present invention comprises a predominantly copper outer layer and a predominantly zinc lining that is adjacent to the lead core of a bullet. The bullet jacket is formed by roll bonding or cladding a predominantly zinc layer to a predominantly copper layer and shaping, by conventional means, the bi-metallic combination into a bullet jacket. In one embodiment, the predominantly zinc layer of the bullet jacket should not exceed about 30% by weight of the weight bullet jacket, and the predominantly copper layer should not be less than about 70% by weight of the weight bullet jacket. Significant deviation from these guidelines may adversely affect the performance of a bullet employing the bullet jacket.
The bullet of the present invention comprises a bullet jacket formed as described above, and further comprises a substantially lead bullet core. Conventional means for seating and encasing lead bullet core within copper jackets are used to seat the bullet cores of the present invention within the bullet jacket of the present invention. A bullet thus made has several advantages over standard bullets and over bullets containing no lead at all.
As previously discussed, the lead from standard bullets left outside after being fired reacts with the environment causing significant contamination to soil and water. However, when bullets of the present invention are similarly discarded, the zinc lining of the present bullet jacket acts like a battery anode and prevents the lead core from reacting with the environment, thereby preventing environmental contamination of soil and water. As previously discussed, the presence of a jacket over the lead core, also helps to reduce the levels of lead dust occurring upon impact.
The fact that a bullet according to the present invention is environmentally safe while continuing to use a lead core provides several advantages over other bullets. First, because the bullet contains a lead core, it maintains the mass and shape of a standard bullet. Consequently, the performance characteristics of the presently designed bullet, in terms of stopping power and flight, do not differ significantly from standard bullets. Bullets having the present bullet jacket therefore do not require any significant design changes or the collateral expenses associated with new designs that leadless bullets often require. Further, because the lead cores of the present invention are of the type normally used in standard bullets, there is no requirement to design and manufacture unique bullet cores. Therefore, the additional expenses in design and manufacture that would be necessitated by unique bullet cores are avoided by the present invention.